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• How to ensure that no non-ascii unicode characters are entered ?

  - by Jacques René Mesrine

  Given a java.lang.String instance, I want to verify that it doesn't contain any unicode characters that are not ASCII alphanumerics. e.g. The string should be limited to [A-Za-z0-9.]. What I'm doing now is something very inefficient: import org.apache.commons.lang.CharUtils; String s = ...; char[] ch = s.toCharArray(); for( int i=0; i<ch.length; i++) { if( ! CharUtils.isAsciiAlphanumeric( ch[ i ] ) throw new InvalidInput( ch[i] + " is invalid" ); } Is there a better way to solve this ?

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• Are there any Python reference counting/garbage collection gotchas when dealing with C code?

  - by Jason Baker

  Just for the sheer heck of it, I've decided to create a Scheme binding to libpython so you can embed Python in Scheme programs. I'm already able to call into Python's C API, but I haven't really thought about memory management. The way mzscheme's FFI works is that I can call a function, and if that function returns a pointer to a PyObject, then I can have it automatically increment the reference count. Then, I can register a finalizer that will decrement the reference count when the Scheme object gets garbage collected. I've looked at the documentation for reference counting, and don't see any problems with this at first glance (although it may be sub-optimal in some cases). Are there any gotchas I'm missing? Also, I'm having trouble making heads or tails of the cyclic garbage collector documentation. What things will I need to bear in mind here? In particular, how do I make Python aware that I have a reference to something so it doesn't collect it while I'm still using it?

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• C++ Memory Allocation & Linked List Implementation

  - by pws5068

  I'm writing software to simulate the "first-fit" memory allocation schema. Basically, I allocate a large X megabyte chunk of memory and subdivide it into blocks when chunks are requested according to the schema. I'm using a linked list called "node" as a header for each block of memory (so that we can find the next block without tediously looping through every address value. head_ptr = (char*) malloc(total_size + sizeof(node)); if(head_ptr == NULL) return -1; // Malloc Error .. :-( node* head_node = new node; // Build block header head_node->next = NULL; head_node->previous = NULL; // Header points to next block (which doesn't exist yet) memset(head_ptr,head_node, sizeof(node)); ` But this last line returns: error: invalid conversion from 'node*' to 'int' I understand why this is invalid.. but how can I place my node into the pointer location of my newly allocated memory?

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• Scaling up an image

  - by codefail

  How do I fulfill the condition "returns the entire scaled up image" If I am coding this correctly, scaleColor handles individual colors, getRed handles the red, etc. I am multiplying this by the input, numTimes, which will create a new image that is scaled up it. This scaled up (increase size) is to be returned. This is what I have. Image Image::scaleUp(int numTimes) const { for (int x = 0; x < width; x++) { for (int y = 0; y < height; y++) { pixelData[x][y].scaleColor(pixelData[x][y].scaleRed(pixelData[x][y].getRed()*numTimes)); pixelData[x][y].scaleColor(pixelData[x][y].scaleGreen(pixelData[x][y].getGreen()*numTimes)); pixelData[x][y].scaleColor(pixelData[x][y].scaleBlue(pixelData[x][y].getBlue()*numTimes)); } } //return Image(); }

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• Convert CString to string (VC6)

  - by Yan Cheng CHEOK

  I want to convert CString to string. (Yup. I know what am I doing. I know the returned string will be incorrect, if CString value range is outside ANSI, but That's Is OK!) The following code will work under VC2008. std::string Utils::CString2String(const CString& cString) { // Convert a TCHAR string to a LPCSTR CT2CA pszConvertedAnsiString (cString); // construct a std::string using the LPCSTR input std::string strStd (pszConvertedAnsiString); return strStd; } But VC6 doesn't have CT2CA macro. How I can make the code to work as well in both VC6 and VC2008?

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• Pass 2d array to function in C?

  - by Evelyn

  I know it's simple, but I can't seem to make this work. My function is like so: int GefMain(int array[][5]) { //do stuff return 1; } In my main: int GefMain(int array[][5]); int main(void) { int array[1800][5]; GefMain(array); return 0; } I referred to this helpful resource, but I am still getting the error "warning: passing argument 1 of GefMain from incompatible pointer type." What am I doing wrong?

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• Objective c key path operators @avg,@max .....

  - by davide

  arr = [[NSMutableArray alloc]init]; [arr addObject:[NSNumber numberWithInt:4]]; [arr addObject:[NSNumber numberWithInt:45]]; [arr addObject:[NSNumber numberWithInt:23]]; [arr addObject:[NSNumber numberWithInt:12]]; NSLog(@"The avg = %@", [arr valueForKeyPath:@"@avg.intValue"]); This code works fine, but why? valueForKeyPath:@"@avg.intValue" is requesting (int) from each NSNumber, but we are outputting a %@ string in the log. If i try to output a decimal %d i get a number that possibly is a pointer to something. Can somebody explain why the integers become NSNumbers when i call the @avg operator?

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• llvm clang struct creating functions on the fly

  - by anon

  I'm using LLVM-clang on Linux. Suppose in foo.cpp I have: struct Foo { int x, y; }; How can I create a function "magic" such that: typedef (Foo) SomeFunc(Foo a, Foo b); SomeFunc func = magic("struct Foo { int x, y; };"); so that: func(SomeFunc a, SomeFunc b); // returns a.x + b.y; ? Note: So basically, "magic" needs to take a char*, have LLVM parse it to get how C++ lays out the struct, then create a function on the fly that returns a.x + b.y; Thanks!

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• How do you write byte[] array using log4.net

  - by like.no.other

  Hi, I have a byte[] with some data in it, I would like to write this byte array AS-IS to the log file using log4.net. The problems that i am facing is that There are no overload for byte[] in TextWriter, so even implementing an IObjectRenderer is of no use. I dont have access to the underlying Stream object of Log4.net Also tried converting byte[] into char[] still when i write it, it adds an extra byte. Is this even possible with Log4.net. Thanx in Advance.

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• deleting dublicates in listview delphi

  - by radick

  hi all I am trying to remove dublicates in my listview my function like this below procedure RemoveDuplicates(const LV:TbsSkinListView); var i,j: Integer; begin LV.Items.BeginUpdate; LV.SortType := stText; try for i := 0 to LV.Items.Count-1 do begin for j:=i+1 to LV.Items.Count-1 do begin if SameText(LV.Items[i].SubItems[0], LV.Items[j].SubItems[0]) and SameText(LV.Items[i].SubItems[1], LV.Items[j].SubItems[1]) and SameText(LV.Items[i].SubItems[2], LV.Items[j].SubItems[2]) and SameText(LV.Items[i].SubItems[3], LV.Items[j].SubItems[3]) then LV.Items.Delete(j); end; end; finally LV.SortType := stNone; LV.Items.EndUpdate; end; ShowMessage('Deleted'); end; but its not doing what i intended can anyone help me ?

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• Get the lua command when a c function is called

  - by gamernb

  Supposed I register many different function names in Lua to the same function in C. Now, everytime my C function is called, is there a way to determine which function name was invoked? for example: int runCommand(lua_State *lua) { const char *name = // getFunctionName(lua) ? how would I do this part for(int i = 0; i < functions.size; i++) if(functions[i].name == name) functions[i].Call() } int main() { ... lua_register(lua, "delay", runCommand); lua_register(lua, "execute", runCommand); lua_register(lua, "loadPlugin", runCommand); lua_register(lua, "loadModule", runCommand); lua_register(lua, "delay", runCommand); } So, how do I get the name of what ever function called it?

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• Unable to create unmanaged object using new keyword in managed C++

  - by chair79

  Hi all, I've created a class with a boost::unordered_map as a member, Linkage.h #ifndef LINKAGE_H #define LINKAGE_H #include <boost/unordered_map.hpp> class Linkage { private: boost::unordered_map<int, int> m_IOMap; public: .... }; Linkage.cpp #include "stdafx.h" ... // methods and in the managed side of C++, I try to create the pointer of the obj: private: System::Void Form1_Load(System::Object^ sender, System::EventArgs^ e) { Linkage* m_pLink = new Linkage(); ..... } However this produces errors: Error 4 error LNK2005: "private: static unsigned int const boost::detail::type_with_alignment_imp<4>::found" (?found@?$type_with_alignment_imp@$03@detail@boost@@$$Q0IB) already defined in Proj_Test.obj Linkage.obj ..... Error 7 fatal error LNK1169: one or more multiply defined symbols found Could anyone explain to me pls? Thanks.

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• IE error with jquery counter plugin

  - by Mankey

  I've implemented a jquery counter script (count up from say 50 to 100 with different increments) that I found from this question: jQuery counter to count up to a target number The scripts works great except for in Internet Explorer 8 (and possibly other IE versions?). Here's an error message from IE with the URL to the creator of the script's demo. Message: 'undefined' is null or not an object Line: 32 Char: 17 Code: 0 URI: http://www.ulmanen.fi/stuff/counter.php I'm just wondering if anyone know how this can be fixed. I'm guessing it has to do with el.html() not finding any data but I can't really figure this out. Thanks for any help ^^ I would reply to that post if I could but I can't seem to find any way of doing so (I'm new to stackoverflow, I think I lack privileges).

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• Typical text encoding and EOL behavior on mobile devices

  - by Dan W

  Typical things to worry about when dealing with text are the BOM/signature, encoding, and the end of line (EOL) char/chars. I know that Windows often favours \r\n (CR+LF) and Mac/Linux favours \n (LF), but how about popular mobile devices such as the iPhone and Android? Do typical apps on those platforms favour one or the other (or maybe even \r for iOS)? I'll supply both types to the user just in case, but I'd like to choose one as default. Also, which text encodings are mobiles most likely to use - UTF-8, iso-8859-1, Windows 1252 (or other default codepage) or maybe even UTF-16? And if they use UTF-8/16, are they likely to need (or require not having) a BOM/signature? What is the typical behavior here? Once again, I'll supply a range of encodings to the user just in case, but I'd like to prioritize or use certain encodings as default if it's appropriate.

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• Why does this give a segmentation fault?

  - by nightcracker

  I'm stunned, why does this code give me a segmentation fault? #include <stdio.h> #define LIMIT 1500000 typedef struct { int p; int a; int b; } triplet; int main(int argc, char **argv) { int i; triplet triplets[LIMIT]; for (i = 0; i < 5; i++) { triplets[i].p = 9; // remove this line and everything works fine } printf("%d\n", triplets[15].p); return 0; } EDIT: After changing LIMIT to 150 I no longer get a segmentation fault, it prints random numbers instead.

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• [C++] instantiating bitset using hex character.

  - by bndz

  Hey, I'm trying to figure out how to instantiate a 4 bit bitset based on a hex character. For instance, If I have a character with value 'F', I want to create a bitset of size 4 initialized to 1111 or if it is A, i want to initialize it to 1010. I could use a bunch of if statements like so: fn(char c) { bitset<4 temp; if(c == 'F') temp.set(); //... if(c == '9') { temp.set(1); temp.set(3); } //... } This isn't efficient, is there a way of easily converting the string to a decimal integer and constructing the bitset using the last 4 bits of the int? Thanks for any help.

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• difference fixed width strings and zero-terminated strings

  - by robUK

  Hello, gcc 4.4.4 c89 I got into a recent discussion about "fixed width strings" and "zero terminated strings". When I think about this. They seem to be the same thing. A string with a terminating null. i.e. char *name = "Joe bloggs"; Is a fixed width string that cannot be changed. And also has a terminating null. Also in the discussion I was told that strncpy should never been used on 'zero terminated strings'. Many thanks for any susgestions,

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• Does replacing statements by expressions using the C++ comma operator could allow more compiler opti

  - by Gabriel Cuvillier

  The C++ comma operator is used to chain individual expressions, yielding the value of the last executed expression as the result. For example the skeleton code (6 statements, 6 expressions): step1; step2; if (condition) step3; return step4; else return step5; May be rewritten to: (1 statement, 6 expressions) return step1, step2, condition? step3, step4 : step5; I noticed that it is not possible to perform step-by-step debugging of such code, as the expression chain seems to be executed as a whole. Does it means that the compiler is able to perform special optimizations which are not possible with the traditional statement approach (specially if the steps are const or inline)? Note: I'm not talking about the coding style merit of that way of expressing sequence of expressions! Just about the possible optimisations allowed by replacing statements by expressions.

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• gcc, UTF-8 and limits.h

  - by bobby

  My OS is Debian, my default locale is UTF-8 and my compiler is gcc. By default CHAR_BIT in limits.h is 8 which is ok for ASCII because in ASCII 1 char = 8 bits. But since I am using UTF-8, chars can be up to 32 bits which contradicts the CHAR_BIT default value of 8. If I modify CHAR_BIT to 32 in limits.h to better suit UTF-8, what do I have to do in order for this new value to come into effect ? I guess I have to recompile gcc ? Do I have to recompile the linux kernel ? What about the default installed Debian packages, will they work ?

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• How to keep historic details of modification in a database (Audit trail)?

  - by mada

  I'm a J2EE developer & we are using hibernate mapping with a PostgreSQL database. We have to keep track of any changes occurs in the database, in others words all previous & current values of any field should be saved. Each field can be any type (bytea, int, char...) With a simple table it is easy but we a graph of objects things are more difficult. So we have, speaking in a UML point of view, a graph of objects to store in the database with every changes & the user. Any idea or pattern how to do that?

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• Is Boost.Tuple compatible with C++0x variadic templates ?

  - by Thomas Petit

  Hi, I was playing around with variadic templates (gcc 4.5) and hit this problem : template <typename... Args> boost::tuple<Args...> my_make_tuple(Args... args) { return boost::tuple<Args...>(args...); } int main (void) { boost::tuple<int, char> t = my_make_tuple(8, 'c'); } GCC error message : sorry, unimplemented: cannot expand 'Arg ...' into a fixed-length argument list In function 'int my_make_tuple(Arg ...)' If I replace every occurrence of boost::tuple by std::tuple, it compiles fine. Is there a problem in boost tuple implementation ? Or is this a gcc bug ? I must stick with Boost.Tuple for now. Do you know any workaround ? Thanks.

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• Put logic behind generated LinqToSql fields

  - by boris callens

  In a database I use throughout several projects, there is a field that should actually be a boolean but is for reasons nobody can explain to me a field duplicated over two tables where one time it is a char ('Y'/'N') and one time an int (1/0). When I generate a datacontext with LinqToSql the fields off course gets these datatypes. It would be nice if I don't have to drag this stupid choice of datatype throughout the rest of my application. Is there a way to give the generated classes a little bit of logic that just return me return this.equals('Y'); and return this==1; Preferably without having to make an EXTRA field in my partial class. It would be a solution to give the generated field a totally different name that can only be accessed through the partial class and then generate the extra field with the original name with my custom logic in the partial class. I don't know how to alter the accesibility level in my generated class though.. Any suggestions?

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• Assigning a view controller to be the delegate of a subview which is not directly descendent?

  - by ambertch

  I am writing an iphone app where in numerous cases a subview needs to talk to its superview. For example: View A has a table view that contains photos A has a subview B which allows users to add photos, upon which I want to auto append them to A's table view So far I have been creating a @protocol in B, and registering A as the delegate. The problem in my case is that B has a subview C that allows users to add content, and I want actions in C to invoke changes in its grandparent, A. Currently I am working around this by passing around a self pointer to my base view controller (C.delegate = B.delegate), but it doesn't seem very proper to me. Any thoughts? (and/or general advice on code organization when all sort of subviews needs to talk to superviews would be greatly appreciated) Thanks!

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• IO completion port key confusion

  - by Richard Tew

  I'm writing an IO completion port based server (source code here) using the Windows DLL API in Python using the ctypes module. But this is a pretty direct usage of the API and this question is directed at those who have a knowledge of IOCP, not Python. As I understand the documentation for CreateIoCompletionPort, you specify your "user defined" completion key when you call this function with a file handle (in my case a socket) you are associating with the created IOCP. When you get around to calling GetQueuedCompletionStatus, you get a completion key value along with a pointer to an overlapped object. The completion key should identify what overlapped object and request has completed. However, let's say I pass in 100 as the completion key in my CreateIoCompletionPort call with an overlapped object. When the same overlapped object has its IO completed and it arrives back through GetQueuedCompletionStatus, the completion key that accompanies it is much larger and bares no resemblance to the original value of 100. Am I misunderstanding how the completion key works, or must I be doing it wrong in the source code I linked above?

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• iSightAudio.plugin error when playing video using MediaPlayer

  - by Elisabeth

  I am working on creating a simple iPhone app that plays a movie via URL. When I Build&Run to test in the simulator, it works fine; as soon as I start playing the movie, I get the following message in the console: [1757:4b03] Cannot find executable for CFBundle/CFPlugIn 0x820ffe0 </Library/Audio/Plug-Ins/HAL/iSightAudio.plugin> (not loaded) [1757:4b03] Cannot find function pointer iSightAudioNewPlugIn for factory 9BE7661E-8AEF-11D7-8692-000A959F49B0 in CFBundle/CFPlugIn 0x820ffe0 </Library/Audio/Plug-Ins/HAL/iSightAudio.plugin> (not loaded) I don't get this error on other programs, so I assume it has something to do with this specific program, which uses the MediaPlayer.framework. Does anyone know what is causing this problem and how to fix it? Thank you

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